Last Updated 26 minutes ago
Filmmaking Dictionary: Letter Q / Quartz Lamp (Tungsten-Halogen)
Definition
In film-lighting usage, a quartz lamp usually means a tungsten-halogen lamp with a quartz envelope. Electricity heats a tungsten filament until it emits light. The quartz tolerates the high operating temperature, while the halogen chemistry helps limit deposits of evaporated tungsten on the envelope.
“Quartz” describes part of the lamp’s construction. It does not specify its wattage, voltage, base, beam angle or fixture. Other lamp technologies can also use quartz, so the word alone is not enough to identify a replacement.
Lamp Versus Lighting Fixture
The lamp is the replaceable light-producing component. The fixture holds it and provides the reflector, housing, electrical connection and any lens or other beam-control parts. A tungsten Fresnel and a tungsten open-face light can both use quartz-halogen lamps while producing different beams.
When a crew member asks for a spare globe, use the fixture’s specified lamp code and electrical rating. Two lamps that fit the same socket can still differ in voltage, filament position, permitted operating position or heat load. Physical fit is not a compatibility test.
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Colour and Dimming
Many professional tungsten film lamps are designed around a nominal 3200K colour temperature at rated operation, but that is not true of every quartz lamp. Read the particular lamp specification.
Dimming a conventional tungsten lamp normally lowers its filament temperature, making the light warmer as output falls. That change may suit a practical lamp effect, but it matters when matching shots. Reducing light with a suitable scrim or ND gel changes output without deliberately cooling the filament.
Quartz-halogen does not mean daylight-balanced. CTB can shift a warm source toward a higher colour temperature, with an accompanying loss of light.
Handling and Replacement
- Disconnect power and allow the lamp and fixture to cool before opening or servicing them.
- Use the lamp type, voltage and wattage approved for the fixture.
- Keep bare fingers off the quartz envelope; use the handling method specified by the manufacturer.
- Keep required lenses, screens and protective covers fitted and intact.
- Observe the fixture’s clearance and operating-position requirements, including clearance from gels and fabrics.
A halogen lamp can fail violently. The fixture’s protective enclosure and correct handling are part of the system, not optional accessories. Damaged equipment should be taken out of service for inspection.
Practical Example
A tungsten Fresnel has been dimmed to suit an interview exposure, but now looks noticeably warmer than another unit. Before adding colour correction, the gaffer checks whether the two lamps are operating at different dimmer levels. Matching lamp operation and then controlling output can solve a different problem from changing gel strength.
The lighting department guide explains who handles lighting preparation, operation and coordination on set.
Related Terms
- Fresnel
- 3200K Colour Temperature
- CTB (Color Temperature Blue)
- Neutral Density (ND) Gel
- Lamp Operator
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